Punch stripper apparatus



30, 1966 L. v. WHISTLER, SR, ETAL 3, 69, 38

PUNCH S TRIPPER APPARATUS 2 Sheets-Sheet 1 Filed Dec. 2, 19 4 Wm vmINVENTORS, Lfiwnewca WHISTLER, SR.

L-fl UHcsrLE, J1.

BY awn-1 ATTORNEYS Aug. 30, 1966 v w s 5 ET AL 3,269,238

PUNCH STRIPPER APPARATUS 2 Sheets-Sheet 2 Filed Dec. 2, 1964 o INVENTOR8, AM/Reva ld nsnsz 82.

Ow V S QM L mm M U J E C N E M F A M Q B United States Patent Officeamazes Patented August 30, 1965 PUNCH STRIPPER APPARATUS Lawrence V.Whistler, Sr., 251 Doncaster Road, and Lawrence V. Whistler, In, 259Doncaster Road, both of Kenmore, NCY.

Filed Dec. 2, 1964, Ser. No. 415,250 8 Claims. (Cl. 83-139) The presentinvention relates to new and novel punch stripper apparatus and moreparticularly to a stripper device incorporating a novel retainer meansarrangement for mounting the stripper means in operative position insurrounding relationship to a punch and the like.

The stripper arrangement of the present invention is so constructed andarranged as to be utilized with punches such as those used in piercing,perforating, notching operations and the like, wherein the stripperdevice strips off the workpiece in a well known manner.

The present invention contemplates the use of a stripper deviceincorporating a body of elastic material such as polyurethane and thelike or a more conventional type arrangement wherein compression springmeans is employed.

Stripper devices of the type according to the present invention havebeen secured in operative position about an associated punch in avariety of manners. In some instances, the stripper device ismechanically locked in place by means of a set screw or similararrangement. In some instances, the punch may be provided with aperipheral groove for receiving a suitable attaching means for securingthe stripper device in operative position.

In the present invention, no alteration or change of a conventionalpunch is required, and the stripper device may be quickly and easilymounted in operative position simply by slipping the device into itsoperative clamping position by sliding it over the punch.

While it is highly desirable to provide a punch stripper device whichcan be easily moved into operative position, the same stripper deviceshould remain in operative position, and accordingly, it is desirable toprovide an arrangement whereby a considerable amount of force isrequired to remove the stripper device.

Additionally, it is important to provide an arrangement wherein thestripper apparatus retaining means provides constant holding powerregardless of the position on the punch. In other words, the same amountof force should be required for removing the stripper device throughoutthe length of the portion of the punch upon which the stripper device isadapted to be mounted.

Another important consideration is the fact that punches employed inthis type of operation often have the surface thereof covered with oilor grease and other kinds of lubricants. The retaining arrangementshould be such that the same amount of force is required to remove thestripper apparatus once it is in operative position regardless ofwhether the punch is dry or is provided with some sort of a lubricatingsubstance on the outer surface thereof.

In the arrangement of the present invention, a unique retainer means isemployed which permits the stripper apparatus to be readily mounted inoperative position on a punch simply by sliding the stripper apparatusinto its operative position. A considerable amount of force is requiredto remove the stripper apparatus from an associated punch, but it can bereadily manually removed preferably by twisting the apparatus withrespect to the punch and pulling it downwardly away from the punch.

The retainer means of the present invention provides a constant holdingpower regardless of the position of the stripper apparatus of the punch,and furthermore this holding power is not aflected by the presence oflubricants on the outer surface of the punch.

The retainer means itself comprises a flat disc-like one-piececonstruction formed of relatively rigid resilient material wherein theinner area thereof is provided with a plurality of angularly spacedradially inwardly extending portions the inner ends of which define acentral hole which is undersized to the punch for snugly receiving thepunch and clamping the punch stripper apparatus in operative position onthe punch. Means is incorporated in the stripper apparatus forpermitting flexing of the inner part of the retainer means so that itcan readily move into its operative clamping position.

This construction also permits the holding force to be predetermined andthe holding force of the retainer means can be varied by changingcertain critical dimensions thereof thereby affording great versatilityto this arrangement.

A particularly important economic advantage of the present invention isthe fact that the structure for holding the stripper apparatus inoperative position is extremely simple and inexpensive so that italfords considerable savings in cost while at the same time affordingmaximum utility and a most practical arrangement.

An object of the present invention is to provide new and novel punchstripper apparatus for stripping off work from punches utilized forexample in piercing, perforating and notching operations and the like.

Another object of the invention is the provision of punch stripperapparatus incorporating retaining means for quickly and easily mountingthe stripper device on a punch and for securely retaining the stripperdevice in operative position.

Still another object of the invention is to provide punch stripperapparatus incorporating retainer means which provides a substantiallyconstant holding power regardless of the position of the stripperapparatus on the punch, and further wherein considerable force isrequired to remove the stripper apparatus from the punch.

Still another object of the invention is the provision of punch stripperapparatus incorporating retainer means providing a substantiallyconstant holding power on the punch which is not materially aflFected bythe presence of lubricants or the like on the outer surface of thepunch.

Still another object of the present invention is to provide punchstripper apparatus incorporating retainer means of such a constructionthat the holding force can be predetermined and readily obtained byaltering the dimensions of the retainer means.

A still further object of the invention is the provision of punchstripper apparatus which is quite simple and inexpensive in constructionand yet is at the same time eificient and reliable in use.

Other objects and many attendant advantages of the invention will becomemore apparent when considered in connection with the specification andaccompanying drawings, wherein:

FIG. 1 is a vertical section through punch stripper apparatus accordingto the present invention prior to its installation on an associatedpunch;

FIG. 2 is a sectional View through a punch and die assembly with thestripper apparatus of the present invention illustrated in operativeposition on the punch of the arrangement;

FIG. 3 is a sectional view taken substantially along line 33 of FIG. 1looking in the direction of the arrows;

FIG. 4 is an enlarged sectional view of a portion of the punch stripperapparatus of the present invention illustrating the manner in which theretainer means is adapted to flex into its operative clamping position;

FIG. 5 illustrates the position of the retainer means as the punchstripper apparatus of the present invention is being removed from anassociated punch;

FIG. 6 is a vertical section through a modified form of the invention;and

FIG. 7 is a sectional view taken substantially along line 77 of FIG. 6looking in the direction of the arrows.

Referring now particularly to FIGS. 1-5 inclusive, a first modificationof the invention is illustrated wherein a punch holder 10 supports apunch retaining pad 12, retaining screws 14 being employed for holdingthe punch retaining pad in operative position, and dowel pins 16 beingprovided for properly aligning the punch retaining pad in a conventionalmanner.

A punch indicated generally by reference numeral 20 is inserted in theusual punch receiving hole 21 provided in punch retaining pad 12, ahardened back-up plate 22 being provided against which the upper end ofthe punch rests. The punch may be retained within the punch retainingpad in any suitable conventional manner (not shown) such as a set screwor the like for holding the punch in position.

Punch 20 includes a general cylindrical portion 26 and a lower workingend portion 28 as seen in FIG. 2, and the punch stripper apparatus ofthe present invention is illustrated generally by reference numeral 30and is adapted to be mounted in surrounding relationship to the punch.

A die holder 32 is adapted to support a die retaining pad 34, the dieretaining pad being held in place by retaining screws 36 and properlyaligned by dowel pins 38 in the usual manner. A die bushing 40 ismounted within the usual hole 42 provided in the die retaining pad 34.The construction and arrangement of the punch and die mounting means isof a conventional construction, and forms no part of the presentinvention.

The novel punch stripper apparatus of the present invention indicatedgenerally by reference numeral 30 includes a first relatively rigid endportion 50 and a second relatively rigid end portion 52, a resilientmeans 54 being interposed between the opposite end portions and inengagement therewith. The body of elastic material 54 may comprise apolyurethane plastic which is of generally annular construction havingan outer cylindrical configuration with a longitudinally extending bore56 formed therethrough.

The end portion 50 is provided with a recess 60 opening downwardlytherefrom as seen in FIG. 1, a bead 62 being formed peripherally aboutthe bottom portion of the recess and extending inwardly therefrom so asto retain the upper portion of the elastic body portion 54 snugly withinthe recess in the end portion 50 and to lock the end portion onto thebody portion 54. The recess 60 includes a bottom wall portion 64 whichis substantially flat for a purpose hereinafter described, and endmember 50 is provided with a central hole 66 formed therethrough whichis in communication with the recess 60.

The opposite end portion 52 is provided with a recess 70 for receivingthe lower end of the body portion 54, and a radially inwardly extendingbeam 72 extends peripherally around the upper portion of the recess asseen in FIG. 1 for retaining the end portion 52 on the lower end of thebody portion 54. End portion 52 is also provided with a central hole 74formed therethrough. It will be noted that the bore 56 as well as theholes 66 and 74 are aligned with one another so as to receive a punchtherewithin when the stripper apparatus is mounted in operative positionas shown in FIG. 2. Each of the end portions 50 and 52 may be formed ofa suitable relatively rigid material such as mild steel. The retainermeans of this modification is indicated generally by reference numeral80, the retainer means being formed for example of tempered spring steelhaving a thickness of approximately .005 of an inch.. Accordingly, thisretainer means is formed of a relatively rigid yet resilient materialand comprises a flat, disc-like one-piece member. This flat member isadapted to rest against the flat bottom wall 64 of recess so as tonormally hold the retainer means in a flat planar position as seen inFIG. 1.

Referring particularly to FIG. 3, the configuration of retainer meansmay be seen more clearly. The retainer means has an outer peripherywhich is generally smaller than the periphery of the inner wall 78 ofthe recess 60. The retainer means is provided with a plurality ofoutwardly extending projections 82 shown as being three in number andangularly spaced an equal amount from one another, these projections 82engaging the wall 78 for holding the retainer means in proper centeredrelationship within the recess. The retainer means is preferably a slipfit within the recess 60.

The inner area of the retainer means is provided with a plurality ofradially extending slots 83 which divide such inner area into aplurality of angularly spaced radially inwandly extending portions 84,the inner ends 86 of which define a circular area within which the punchis adapted to fit. This central hole defined by the inner ends 86 of theportions 84 of the retainer means is slightly undersized to the punch.so as to snugly fit thereon.

In a typical example wherein the punch portion 26 has a diameter of.500' inch, the hole 66 in end portion 50 may have a diameter ofapproximately .502 inch, and the bore 56 formed within the elastic bodyportion 54 may have a diameter of approximately .510 inch, while thecentral hole defined within the retainer means for receiving the punchmay have a diameter of approximately .497 inch.

When the punch stripper apparatus is moved into the operative positionillustrated in FIGS. 2 and 4 wherein the upper surface of end portion 50is disposed against the undersurface of punch retaining pad 12, theretainer means 80 is caused to move into the position shown in FIGS. 2and 4 wherein the inner parts of portions 84 of the retainer means areflexed downwardly, the resilient material of body portion 54 permittingsuch flexing into the position shown in FIGS. 2 and 4. It will be notedin this position as shown in FIG. 4 that the relatively sharp edges 80formed at the upper part of portions 84 engage the outer surface of thepunch for retaining the stripper apparatus in operative position. Whenthe stripper apparatus is pulled downwandly to remove the stripperapparatus from the punch, the retainer means moves into the positionshown in FIG. 5 wherein it tends to become substantially flat, the flatbottom wall 64 of the recess serving to prevent the retainer means innerportions from flexing into an opposite position from that shown in FIGS.2 and 4, and causing a considerable amount of force to be required forremoving the stripper apparatus.

Referring now to FIGS. 6 and 7 of the drawings, a modified form of theinvention is illustrated wherein a punch retainer is provided, thispunch retainer being of a magnetic type which is adapted to bemagnetically adhered to the punch holder. A piercing punch 102 isprovided which may be substantially identical with the punch 20previously discussed. The punch is provided with a suitable notch 103formed in one side thereof for receiving a set screw 104 threaded withina suitable opening provided in the punch retainer 100 for securing thepunch in operative position within the punch retainer in a well knownmanner.

The stripper apparatus itself is indicated generally by referencenumeral and includes a stripper adaptor 112. A plurality of retainerbolts 114 are slidably mounted within suitable countersunk openings 115provided in the stripper adaptor, the retainer bolts 114 supporting atthe lower ends thereof a stripper plate 116. Conventional coil springs118 are provided around the retainer bolts and are adapted to urge thestripper plate 116 in a downward direction after it has been movedupwardly during a piercing operation so as to subsequently strip off theworkpiece. Stripper adaptor 112 and the stripper plate 116 are providedwith aligned openings 120 and 122 formed therethrough for receiving theadjacent portions of the punch.

Stripper adaptor 112 is provided with a recess 130 in the upper surfacethereof which is adapted to receive a retainer means indicated generallyby reference numeral 132. This retainer means is also of a fiatdisc-like onepiece construction and is formed of a material similar tothe retainer means 80 previously discussed. A flat retainer cap 134 isdisposed over retainer means 132, the flat undersurface of cap 134engaging the upper surface of the retainer means. Retainer cap isretained in position by means of flat head screws 136 extending throughsuitable openings provided in members 134 and 112, and.

a central hole 138 is formed through cap 134 for receiving the punch.

As seen particularly in FIG. 6, the upper inner portion of stripperadaptor 112 is cut away or beveled as indicated by reference numerals140 so as to provide an annular downwardly tapering shoulder which is incommunication with the central part of recess 130. This cut away portion140 permits downward flexing of the inner part of the retainer means sothat it can move into the operative position shown in FIG. 6 which issimilar to that previously discussed wherein the inner portions of theretainer means are flexed downwardly when the retainer means is inoperative clamping position about a punch.

Referring now particularly to FIG. 7, the configuration of the retainermeans 132 may be more clearly seen. The outer peripheral surface of theretainer means is of substantially elliptical configuration so that theouter surface of the retainer means engages the inner wall of the recess130 at two diametrically opposite points of the substantially circularrecess. Here again, the retainer means is substantially a slip fitwithin the recess provided in the stripper adaptor. The inner area ofthe retainer means 132 is provided with a plurality of radiallyextending slots 144 which divide this inner area of the retainer meansinto a plurality of angularly spaced radially inwardly extendingportions 146 the inner ends 148 of which define a central circular holefor receiving a punch. As in the previous modification, the central holeprovided within the retainer means is undersized to the punch so thatthe punch may be tightly gripped by the retainer means for holding thepunch stripper apparatus in operative position.

It will be apparent that in each of the modifications, the provision ofthe radially extending slots in the retainer means provides greaterresilience to the inner area of the retainer means so that it can flexinto the operative position as illustrated in the drawings. It shouldalso be understood that each of the modifications of the inventionoperates in a similar manner to provide the new and improved results asaforesaid.

It is apparent from the foregoing that there is provided according tothe present invention new and novel punch stripper apparatus forstripping ofl work from punches utilized in piercing, perforating,notching operations and the like. The invention incorporates retainermeans for permitting quick and easy mounting of the stripper apparatuson the punch and for securely retaining the stripper apparatus inoperative position. The retainer means of the present invention providesa substantially constant holding power regardless of the position of thestripper apparatus of the punch, and considerable force is required forremoving the stripper apparatus from an associated punch. In addition,the holding power of this type of retainer means is not materiallyaffected by the presence of lubricants and the like on the outer surfaceof the punch. The holding force of the retainer means may be readilyadjusted by varying the size of the hole defined in the central area ofthe retainer means or by increasing or diminishing the thickness of theretainer means. It is accordingly apparent that slight changes in thedimensions of the retainer means can be made so as to substantiallyalter the amount of holding force of the retainer means. In a typicalexample, wherein the dimensions are as aforesaid, regarding the diameterof the punch and the hole provided in the retainer means, and whereinthe retainer means has a thickness of approximately .005 of an inch, aforce of 30 to 40 pounds is required for removing the stripper apparatusfrom an associated punch. It is also apparent that the arrangement ofthe present invention is quite simple and inexpensive in construction,and yet is quite efiicient and reliable in use.

As this invention may be embodied in several forms without departingfrom the spirit or essential characteristics thereof, the presentembodiment is therefore illustrative and not restrictive, and since thescope of the invention is defined by the appended claims, all changesthat fall within the metes and bounds of the claims or that form theirfunctional as well as conjointly cooperative equivalents are thereforeintended to be embraced by those claims.

We claim:

1. Punch stripper apparatus comprising a first relatively rigid endportion and a second relatively rigid end portion spaced from said firstend portion, each of said end portions having a central hole formedtherethrough for receiving a portion of a punch, resilient meansinterposed between and engaging said first and second end portions, saidresilient means defining a central clearance area for receiving a punch,and retainer means adjacent said first end portion for retaining thestripper appaartus on a punch, said retainer means being formed of arelatively rigid resilient material, said retainer means comprising asubstantially flat sheet-like means defining a central hole for snuglyengaging an associated punch and being of such thickness that it isadapted to flex in opposite directions while in .gripping engagementwith an associated punch, said retainer means defining a first surfacefacing toward said second end portion and an opposite surface facingtoward said first end portion, and a flat surface engaging said oppositesurface of the retainer means, said retainer means extending radiallyinwardly of said fiat surface only a very small distance whereby saidflat surface tends to prevent flexing of said retainer means in adirection to release the stripper apparatus from an associated punch.

2. Apparatus as defined in claim 1 wherein said retainer means includesan inner area defining a plurality of spaced portions the inner surfacesof which are spaced to provide said central hole.

3. Apparatus as defined in claim 2 wherein said spaced portions of saidinner area comprise a plurality of inwardly extending portions which areangularly spaced from one another and which have a greater degree offlexibility and resiliency than the port-ions of the retainer meansdisposed outwardly thereof.

4. Apparatus as defined in claim 1 wherein said resilient meanscomprises a body formed of elastic material, each of said end portionshaving a recess formed therein for receiving one end portion of saidbody, said retainer means being disposed within the recess of said firstend portion and being interposed between said body of elastic materialand the associated end :portion.

5. Apparatus as defined in claim 1 wherein said resilient meanscomprises compression spring means, means for limiting movement of saidend portions away from one another, said retainer means being clamped inoperative position in contact wth said first end portion.

6. Apparatus as defined in claim 5 wherein said first end portion isprovided with a cutaway portion adjacent said retainer means forpermitting flexing of the inner portions of the retainer means when ingripping engagement with an associated punch.

7. Apparatus as defined in claim '1 wherein said one end ReferencesCited by the Examiner portion ineludes a recess, said retainer meansbeing dis- UNITED STATES PATENTS posed within said recess and includinga plurality of spaced 5 42 2/ 4O 1 83 6 outwardly extending projectionswhich are in engagement 2,22 1 19 t 13 2,712,262 7/1955 Knohl 8536 withthe wall of said recess. 5 2 60 8 8. Apparatus as defined in claim 1wherein said one end 1 ffg 2 7*115 portion is provided with a recess,said retainer means $102,508 9/ 9 3 85 36 being disposed within saidrecess, the outer periphery of 3211035 10/1965 Whistler et 83 139 saidretainer means being substantially elliptical in configuration andengaging spaced portions of the wall of 10 WILLIAM DYER Primary Exammer'said recess. L. B. TAYLOR, Assistant Examiner.

1. PUNCH STRIPPER APPARATUS COMPRISING A FIRST RELATIVELY RIGID ENDPORTION AND A SECOND RELATIVELY RIGID END PORTION SPACED FROM SAID FIRSTEND PORTION, EACH OF SAID END PORTIONS HAVING A CENTRAL HOLE FORMEDTHERETHROUGH FOR RECEIVING A PORTION OF A PUNCH, RESILIENT MEANSINTERPOSED BETWEEN AND ENGAGING SAID FIRST AND SECOND END PORTIONS, SAIDRESILIENT MEANS DEFINING A CENTRAL CLEARANCE AREA FOR RECEIVING A PUNCH,AND RETAINER MEANS ADJACENT SAID FIRST END PORTION FOR RETAINING THESTRIPPER APPARATUS ON A PUNCH, SAID RETAINER MEANS BEING MEANS OF ARELATIVELY RIGID RESILIENT MATERIAL, SAID RETAINER MEANS COMPRISING ASUBSTANTIALLY FLAT SHEET-LIKE MEANS DEFINING A CENTRAL HOLE FOR SNUGLYENGAGING AN ASSOCIATED PUNCH AND BEING OF SUCH THICKNESS THAT IT ISADAPTED TO FLEX IN OPPOSITE DIRECTIONS WHILE IN GRIPPING ENGAGEMENT WITHAN ASSOCIATED PUNCH, SAID RETAINER MEANS DEFINING A FIRST SURFACE FACINGTOWARD SAID SECOND END PORTION AND AN OPPOSITE SURFACE FACING TOWARDSAID FIRST END PORTION, AND A FLAT SURFACE ENGAGING SAID OPPOSITESURFACE OF THE RETAINER MEANS, SAID RETAINER MEANS EXTENDING RADIALLYINWARDLY OF SAID FLAT SURFACE ONLY A VERY SMALL DISTANCE WHEREBY SAIDFLAT SURFACE TENDS TO PREVENT FLEXING OF SAID RETAINER MEANS IN ADIRECTION TO RELEASE THE STRIPPER APPARATUS FROM AN ASSOCIATED PUNCH.